On 12 December 2013 10:56, David VanHorn wrote: > Where are the snubbers? I suspect you need them at the coils, and at th= e > chip through the common diode into a zener to ground. > Plus the ULN2803 has on board "catch diodes" - all connected to pin 9 if I have the mental image correct - diagonally opposite pin 1. Connect this to Vdd or to Vdd via a resistor or to ground via a zener or ... . What you are doing sounds OK. What is the Vin drive voltage? Various members of the family have different input circuits and it is possible to destroy some by overvoltage input. Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .